Equivalence of labeled graphs and lattices

A. N. Bhavale1
1Department of Mathematics, PES Modern College of Arts, Science and Commerce, (Autonomous), Shivajinagar, Pune 411005, (affiliated to Savitribai Phule, Pune University, Pune 411007), Maharashtra, India

Abstract

In \(1973\), Harary and Palmer posed the problem of enumeration of labeled graphs on \(n \geq 1\) unisolated vertices and \(l \geq 0\) edges. In \(1997\), Bender et al. obtained a recurrence relation representing the sequence \(A054548\)(OEIS) of labeled graphs on \(n \geq 0\) unisolated vertices containing \(q \geq \frac{n}{2}\) edges. In \(2020\), Bhavale and Waphare obtained a recurrence relation representing the sequence of fundamental basic blocks on \(n \geq 0\) comparable reducible elements, having nullity \(l \geq \lfloor \frac{n+1}{2} \rfloor\). In this paper, we prove the equivalence of these two sequences. We also provide an edge labeling for a given vertex labeled finite simple graph.

Keywords: chain, lattice, digraph, labeled graph